‘5-Second Rule’ is False, Rutgers Scientists Determine

No, the 5-second rule isn't really accurate. If you drop food on the floor, bacteria can begin transferring onto it in less than one second, Rutgers University researchers found.

Researchers in Rutgers' food science department recently tested four surfaces (stainless steel, ceramic tile, wood and carpet) and four different foods —(watermelon, bread, bread and butter, and gummy candy). The bacteria they used was Enterobacter aerogenes, a cousin of salmonella that naturally occurs in the human digestive system.

The watermelon picked up the most bacteria and became contaminated the fastest, within less than one second, they found. Gummy candy was the least contaminated.

“Transfer of bacteria from surfaces to food appears to be affected most by moisture,” said Donald Schaffner, a professor of food science who led the study. “Bacteria don’t have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer ... We decided to look into this because the practice is so widespread. The topic might appear ‘light’ but we wanted our results backed by solid science.”

Where's the safest place to drop food and then eat it again? Surprisingly, the carpet. Foods dropped on the carpet picked up the least amount of bacteria, the researchers found.

Their findings will appear in the American Society for Microbiology’s journal.

Photo By Evan-Amos - Own work, Public Domain.